This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Objective: To 1) develop strategies for creating genetically identical monkeys using blastomere separation and 2) propagate a family of MHC-defined monkeys using assisted reproductive technologies. The nonhuman primate is a valuable model for examining human disease. The benefits to research, however, are reduced by the inherent variability among animals, which could be minimized by the use of genetically identical animals. Our primary goal was to produce identical rhesus macaque twins. Embryos were produced by in vitro fertilization of oocytes aspirated from follicles after controlled ovarian stimulation. Twins were derived by blastomere separation at the 4- to 14-cell stage in [unreadable]Ca, -Mg media and the blastomeres were reaggregated into 2 empty zona pellucida. Embryos that successfully proliferated after splitting underwent laparoscopic transfer to recipients receiving progesterone implants or injections. However, no term pregnancies were obtained with these split embryos. An additional trial with cleavage stage embryos biopsied by zona drilling and blastomere aspiration was added to define the effect of embryo manipulation on pregnancy outcome. Of 22 transfers of biopsied embryos with injected progesterone supplementation, four healthy singleton infants were produced from biopsied embryos following nonsurgical, transcervical transfer. Preimplantation blastomere biopsy could be a valuable approach for defining specific genetic traits in individual primate embryos as further information on the linkage of rhesus genotype with physiological traits is obtained. This project used Animal, CPI, and Assay Services. A publication is pending. Note: AIDS-related.